The present invention relates to an apparatus used in the at-sea retrieval of floating objects such as anchor buoys and seismic buoys. The apparatus of this invention may be used for the purpose of picking up any floating object at sea, such as a buoy, in order to retrieve or reposition a subsea article such as an anchor attached to the buoy, or more simply to retrieve and collect free floating objects.
Anchor buoys are employed, for example to mark the anchors of a pipelaying barge which utilizes the anchors to position itself and maintain itself on course for example, during a pipelaying operation. As the barge lays pipe it becomes periodically necessary to reposition the anchors of the lay barge. This is accomplished by picking up the anchors via cables or other pendent lines attached to the anchor and run through buoys floating on the surface. Pneumatic buoys having a central hawsepipe through which the cable or pendent line passes are commonly used. The anchors are then repositioned with the buoys again marking the new position of the anchors.
In an at-sea pick-up operation of any floating object, the task becomes progressively more difficult as sea conditions worsen. The pick-up is potentially hazardous where personnel are required to be near the rail of an ocean-going vessel while assisting in the retrieval operation. One method to retrieve buoys involves use of an over-the-side capture apparatus utilizing a boom and/or winch to capture the buoy and reposition the anchor. Such an arrangement present difficulty in maneuvering the vessel into position. Since steerage is particularly difficult in a high sea, the efficiency of such an apparatus is markedly reduced when most needed. There is an additional disadvantage to this method caused by the parallax effect of the retrieval apparatus being offset from the centerline of the vessel. Thus the exact placement of the retrieval apparatus is rendered more difficult by having to visually ascertain the track of the vessel and the offset track of such apparatus while allowing for wind and water action.
Another method used is simply for a crew member to physically place a hook on the floating object and then to retrieve the object with a boom and or winch apparatus. This method necessarily involves increased difficulty for crew members and becomes increasingly hazardous and difficult with increasing wave intensity.